This invention relates to piezoceramics and more particularly to piezoelectric generators. More particularly, this invention relates to beneficial applications that can be realized with properly arrayed and configured piezoelectric generators.
Piezoelectrics have two general configurations. First, a piezoelectric actuator may be constructed. Here, the piezoelectric element is physically distorted when an electric potential is placed across the piezoelectric actuator. A piezoelectric actuator may be configured to bend or stretch/compress as a result of an electric potential. Second, a piezoelectric generator may be constructed. Here, the piezoelectric element generates an electric potential when physically distorted (e.g., strained). A piezoelectric generator may be configured to generate an electric potential when the generator is bent or compressed/stretched.
Traditional piezoelectric generators generally produce small voltages. As a result, traditional piezoelectric generators are primarily utilized as sensors (e.g., strain sensors). It is therefore desirable to create piezoelectric configurations that generate a significant electric potential—a potential which may be utilized as a power supply.
Throughout the day, people expel and waste energy. For example, people waste a large amount of energy while walking. In 1995, Thad Starner estimated that 67 watts of power are available in the heel movement of an average sized person (e.g., 68 kg) walking at a brisk pace (e.g., two steps per second with the foot moving 5 cm vertically). See T. Starner, “Human Powered Wearable Computing,” IBM Systems J., vol. 35, nos. 3 and 4, 1996, pp. 618–629. It is therefore desirable to recapture some of the energy wasted during everyday human activities.
Shoe-mounted Piezoelectrics have been developed. See Shenck et al., “Energy Scavenging with Shoe-Mounted Piezoelectrics,” IEEE-Micro, May 2001. These traditional configurations produce small amounts of power. It is therefore desirable to create shoe-mounted piezoelectrics that are capable of generating relatively large amounts of power. It is also desirable to provide piezoelectrics that may be integrated into other types of energy-wasting devices in order to recapture and convert the wasted energy into an electrical, or useful, energy.